Cognitive factors likely play a significant role in the safety of older drivers. Yet little data exists to describe the nature of higher cognitive processes which impact most on the driving performance of older persons. The first aim of this project is to discriminate groups of "high-risk" and normal older drivers on selected cognitive variables. The second aim is to explore the relationship between cognitive functioning and independently, blindly assessed driving skills. It is hypothesized that measures of attention and vigilance will best discriminate older drivers at risk for driving problems. We will evaluate a sample of 100 older drivers and quantify patterns of cognitive impairment which may exist in this group relative to 50 early Alzheimer's Disease patients. In addition to cognitive assessments, we will assess the driving knowledge and skills of these drivers by means of an on-road driver evaluation, as well as their self-evaluation of driving skills. Finally, we will retrospectively assess the driving records of this sample to provide a further, independent index of driver safety. In this way, we will investigate, for normal and high-risk older drivers, the relationship between self-assessments of driver safety, performance on neuropsychological test measures thought to reflect cognitive and perceptual processes most relevant to driving, and an independent assessment of actual driving performance. Our study is thus designed to yield information concerning the relationship between laboratory measures of cognitive functioning and concurrent driving behavior, as well as predictive capacity of the former to assess driving safety. This information can then serve as a foundation for efforts to develop assessments of cognitive functioning that act as valid tools for driver screening in older persons as well as act to more fully describe the aspects of aging that have been theoretically proposed as relevant to driving performance.